ppfunctions.c

ADI 公司的DSP ADSP21262 EZ-KIT LITE开发板的全部源代码

///////////////////////////////////////////////////////////////////////////////////////
//NAME:     ppfunctions.c (AMD Parallel Flash Programmer)
//DATE:     9/18/03
//PURPOSE:  Program the Parallel Flash for the ADSP-21262 Ezkit
//
//USAGE:    This file contains the subroutines used to access external devices the
//          via the parallel port.
//
////////////////////////////////////////////////////////////////////////////////////////
#include "ppflash.h"

//----------------------------------------
//WRITE TO PARALLEL PORT SUBROUTINE
//Writes the specified amount of words to the parallel port
//Inputs -  word_out - address of the buffer holding the 32-bit words to write (pointer)
//          flash_address - address to write to in external memory (pointer)
//          count32 - number of 32-bit words to write.
//Returns- none
//This example writes to only one byte at a time. When sending the flash commands, the
//only one address is required, so the external modify is set to 0.
void writeToPP(int *word_out, int *flash_address, int count32)
{
    //Set up the parallel port for 8-bit writes to external memory
    *pPPCTL = PPTRAN|PPBHC|PPDUR20;

    //Internal DMA address is passed
    *pIIPP = (int) word_out;
    //Internal Modify is always 1
    *pIMPP = 1;
    //Internal count is passed
    *pICPP = count32;

    //External DMA Address is passed
    *pEIPP = (int) flash_address;
    //External Modify is always 0
    *pEMPP = 0;
    //External count is always 4x internal count (PP only transfers 32-bit words)
    *pECPP = (count32 * 4);

    //Enable the PP for transfer
    *pPPCTL |= PPDEN|PPEN;

    //Wait for the interrupt semaphore to get set
    while(!ppInterruptFlag){};

    //Clear the interrupt semaphore and disable the PP
    ppInterruptFlag=0;
    *pPPCTL=0;
}

//----------------------------------------
//READ FROM PARALLEL PORT SUBROUTINE
//Reads the specified amount of words from the parallel port
//Inputs -  flash_address - external byte address to read from (pointer)
//Returns- dataIn - 32-bit word with four copies of the requested byte
//                  Not masked to 1 byte for use with flash polling during programming
//                  (the PP always reads 4 bytes and it is necessary to view 2 consecutive byte
//                   for reading the status of the Flash)
//It is necessary to mask the returned word down to 1 byte (the lowest).
int readFromPP(int *flash_address)
{
    //buffer to hold the incoming data
    int dataIn;

    //Set up the parallel port for 8-bit reads from external memory
    *pPPCTL = PPBHC|PPDUR20;

    //Internal address is that of the buffer dataIn
    *pIIPP = (int) &dataIn;
    //Internal modify is 0, do not corrupt any other internal memory accidentally
    *pIMPP = 0;
    //Only read 1 word at a time
    *pICPP = 1;

    //External address is passed
    *pEIPP = (int) flash_address;
    //External count is zero, only reading one byte at a time
    *pEMPP = 0;
    //External count is always 4x internal count (PP only transfers 32-bit words)
    *pECPP = 4;

    //Enable the PP for transfer
    *pPPCTL |= PPDEN|PPEN;

    //Wait for the interrupt semaphore to get set
    while(!ppInterruptFlag){};

    //Clear the interrupt semaphore and disable the PP
    ppInterruptFlag=0;
    *pPPCTL=0;

    return dataIn;
}